The present invention relates to height adjustable chairs and, in particular, to a height adjustment mechanism for such chairs.
As the users of chairs are of myriad sizes, various aspects of some chairs have been made adjustable. One such aspect is the height of the seat. Typically, the adjustability of the height of the seat is provided by a gas cylinder having two-chambers separated by a normally closed valve. Such a gas cylinder generally terminates in a valve opening member at its top end, which valve opening member is biased to an extended position whereat the valve is closed. A user actuator is supplied to depress the valve opening member in order to open the cylinder valve to permit height adjustment of the seat. A known user actuator comprises a lever tiltably mounted in a housing above the valve opening member. The lever often terminates in a paddle. With such an actuator, the user may depress the valve opening member by raising the paddle. Such an actuator may have a limited range of movement and, therefore, limited granularity in pressure applied when raising the paddle to depress the valve opening member.
A chair height adjustment mechanism includes a lever positioned to overlay a valve opening member of a height adjusting cylinder. The lever may be depressed by a cam on the end of a control arm when the control arm is rotated. When the lever is depressed it depresses the valve opening member.
Advantageously, the control arm of such a chair height adjustment mechanism preferably rotates through about 90 degrees, thereby providing a greater range of movement than typical rod-type chair height adjustment mechanisms. The greater range of movement allows for finer granularity in applying pressure to depress the valve opening member and therefore allows finer adjustments to the chair height.
In accordance with an aspect of the present invention there is provided a height adjustment mechanism for a chair. The height adjustment mechanism includes a second class lever pivotally attached to a main frame, the lever overlying an opening for reception of a valve opening member of a height adjusting cylinder, a control arm supported by the main frame and a cam mounted on the control arm. The cam is positioned to depress the lever, responsive to rotation of the control arm, such that the lever depresses the valve opening member when the valve opening member is received by the opening.
In accordance with an aspect of the present invention there is provided a chair. The chair includes a height adjusting cylinder having a control valve and a valve opening member adapted to open the control valve, a seat and a height adjustment mechanism adapted to secure the seat to the height adjusting cylinder. The height adjustment mechanism includes a second class lever pivotally attached to a main frame, the lever overlying the valve opening member of the height adjusting cylinder, a control arm supported by the main frame and a cam mounted on the control arm. The cam is positioned to depress the lever, responsive to rotation of the control arm, such that the lever depresses the valve opening member.
In accordance with an aspect of the present invention there is provided a height adjustment mechanism for a chair. The height adjustment mechanism includes a pivot bar mounted to a main frame, a lever pivotally attached to the pivot bar, the lever overlying an opening for reception of a valve opening member of a height adjusting cylinder, a control arm supported by the main frame, a cam mounted on the control arm, the cam positioned to depress the lever, responsive to rotation of the control arm, such that the lever depresses the valve opening member when the valve opening member is received by the opening and a biasing member to bias the lever against the cam and away from the opening.
In accordance with an aspect of the present invention there is provided a chair. The chair includes a height adjusting cylinder having a control valve and a valve opening member adapted to open the control valve, a seat and a height adjustment mechanism adapted to secure the seat to the height adjusting cylinder. The height adjustment mechanism includes a pivot bar mounted to a main frame, a lever pivotally attached to the pivot bar, the lever overlying the valve opening member of the height adjusting cylinder, a control arm supported by the main frame, a cam mounted on the control arm, the cam positioned to depress the lever, responsive to rotation of the control arm, such that the lever depresses the valve opening member and a biasing member to bias the lever against the cam and away from the opening.